This invention relates generally to air cleansing devices. More particularly, this invention relates to ultraviolet (UV) irradiation and filtration devices. In particular, the invention deals with the use of ultraviolet radiation to decompose organic molecules that have a tendency to colonize filters and evaporation coils that are utilized to condition the air in enclosed surroundings. Also, the invention deals with the placement of ultraviolet lamps placed within a chamber that has a means for passing air therethrough. The chamber""s walls are polished and as such the UV radiation emitting from the UV lamps is reflected off the chamber walls which results in the decay of organic particles adjacent and within the surround and contained therein. Further, baffles adjacent the UV lamps in the chamber cause turbulence within the air passing therethrough which results in an increase in decay of the organic molecules.
Ultraviolet (UV) light in the form of germicidal lamps has been used since the early 1900""s to kill the same types of microorganisms that typically cause the same types of problems today. Since then, UV radiation in the short wave or C band range (UVC) has been used in a wide range of germicidal applications to destroy bacteria, mold, yeast and viruses. After World War II, the use of WVC rapidly increased. UVC is generally understood to exist in the 180 nm to 280 nm wave length area. Typical examples included hospitals, beverage production, meat storage and processing plants, bakeries, breweries, pharmaceutical production and animal laboratories; virtually anywhere microbial contamination was of concern. Early UVC strategies primarily consisted of an upper air approach. This method directed a beam across the ceiling of a room.
During the 1950""s when tuberculoses infections were on the rise, the use of UVC became a major component in the control and irradiation of TB. It was discovered that by placing UVC lamps in the air handling equipment, they could initially be more effective.
However, certain conditions found within the air handling systems drastically reduced UVC performance. Moving air, especially below 77xc2x0 F., over the tubes decreased the output and service life of conventional UVC products and thus their ability to destroy viable organisms. The use of UVC with airflow systems virtually disappeared over the next decade due to the introduction of new drugs, sterilizing cleaners and control procedures combined with the performance problems of UVC lamps and air handling systems (reduced output, short tube life, and high maintenance). In order for UVC to be effective in the xe2x80x9chostilexe2x80x9d environment of indoor central air circulating systems (or HVAC systems), a new method of producing effective UV had to be developed.
The ability of ultraviolet light to decompose organic molecules has been known for a long time, but it is only recently that UV cleaning of surfaces has been explored. In 1972, it was discovered that ultraviolet light could clean contaminated surfaces. Plus, it was learned that there is a predictable nanometer location of absorption of ozone and organic molecules. It was then learned that the combination of ozone and UV could clean surfaces up to two thousand times quicker than one or the other alone. However, from testing it can be seen that the destructive potential of a combination of UVC and ozone for system components is detrimental. The negative side effects of ozone are now known.
In 1972, tests were conducted using a quartz tube filled with oxygen. A medium pressure mercury (Hg) UV source which generated ozone was placed within centimeters of the tube. A several thousand angstrom thick polymer was exposed to this and was depolymerized in less than one hour. The major products of this reaction were water (H2O) and carbon dioxide (CO2). It was discovered that UV (300 nm and below) and oxygen played a major role in depolymerization. In 1974, research concluded that during such cleaning, the partial pressure of O2 decreased and that of CO2 and H2O increased, suggesting breakdown.
It was also discovered that the absorption coefficient of O2 increases rapidly below 200 nm with decreasing wave lengths. A 184.9 nm wave length (optimal spectral line for ozone generation) is readily absorbed by oxygen, thus leading to the generation of ozone (O3). Ozone may be generated at undetectable levels at other wave lengths below 200 nm. Therefore, radiation emission below 200 nm was found undesirable.
Similarly, most organic molecules have a strong absorption band between 200 nm and 300 nm. A wave length of 253.7 nm is useful for exciting and disassociating contaminant molecules. 265 nm was thought to be the optimal spectral line for germicidal effectiveness. The 253.7 nm wave length is not absorbed by O2; therefore, it does not contribute to ozone generation, but it is absorbed by most organic molecules and by ozone (O3). Thus, when both wave lengths are present, ozone is continually being formed and destroyed. Unfortunately, previously existing lamps operated between 250 nm and 258 nm, peaking at 254 nm, missing out on the optimal 265 nm goal.
As indicated above, the effective killing power of UV seemed to be greatest at 265 nm. However, conventional UV has its maximum intensity at 254 nm. Furthermore, the intensity degrades as a function of temperature and distance. This was due to the conventional tubes being designed as long, straight lamps.
With regard to HVAC systems, biological contaminants are difficult to control because they grow in our moist, indoor environment. The most common strategy is to try to use an effective air system filter to rid indoor air of biological contaminants. While this is an important element of cleaning air, this has its problems. Most filters are inadequate because of the many organisms that pass right on through the filter. Also, any organisms that collect on the filter can form germ colonies that may soon contaminate passing air. Further, if the filter should be too efficient, it blocks the passage of air and creates back pressure, causing the blower to struggle to move air through the system. Furthermore, when the system is turned off, natural temperature differences between the system and indoor air spaces cause convection or back draft flow into the supply ducts (bypassing the filter). This causes contaminants to be pulled back into the duct work, implanting microbes in the air flow duct cavity. These new cultures become added sources of contaminant.
In the past, to try to eliminate the biological contaminants in ducts, a common strategy was to clean the ducts followed by a biocide treatment. But this has its draw backs also. Most biological contaminants return and are active in the treated area within three months. Further, if the system is being treated for severe contamination such as legionela, an acid wash of the coil is common. This is not only expensive, but can shorten the life of the equipment. Furthermore, all biocide used in the ducts are chemical based, leaving potential toxic vapors and chemical pollutants circulating in the system as well. For obvious health reasons, the preferred way to control biological contaminants is through natural, non-polluting strategies.
The term xe2x80x9cair-conditioningxe2x80x9d (A/C) normally refers to cooling the air of a building. An A/C system operates like this: the outdoor portion of the A/C unit compresses a gas to a liquid. During this compression, heat energy is driven out of the liquid. This colder liquid then travels through tubing to the evaporative coil located inside the building proximate the central/furnace fan.
The evaporation coil has numerous rows of fins. The fins are all made of an aluminum alloy that is extremely tough due to an impervious film of oxide on the metal. The fins act as heat exchangers with the circulating air within the system. When this compressed liquid reaches the evaporative coil, the liquid expands and evaporates, converting back to a gas. As it does, it recovers the amount of heat energy lost in the compression cycle. This conversion absorbs heat through the coil fins from the surrounding air that is moving across the fins.
With the blower operating, air moves across the coil fins and is cooled by losing its heat to the evaporation process inside the coil.
If for some reason the central air system becomes less efficient during its operational life, the energy consumption and costs will rise. Since so much energy is involved just in normal use, any change in efficiency will mean a sharp increase in costs.
The evaporative coil is made of tiny, closely fitting fins for cooling the air. These fins are so close, the coil essentially becomes a filter, screening out and collecting dust particles from the air. Indoor airborne organic particles and microorganisms are primarily byproducts of human, animal, insect and microbial output (dead skin, hair, paint flakes, insect feces, carpet fibers, etc.) within the indoor environment. As these particles build up, the space between the fins becomes blocked, thus reducing airflow and restricting cooling efficiency of the coil.
The coil not only collects these particles, but also becomes a bio-nursery for mold and bacteria. When the A/C operates, water condenses onto the evaporative coil fins. This water drains off into a drip pan. Depending on the amount of moisture within the air, the amount of water collected and drained can be typically six gallons per day.
The evaporative coil is mounted in line to the furnace fan housing. Because of its location, the coil housing is very dark and moist. Thusly, it becomes an ideal nursery for the growth of bacteria and mold. Those skilled in the art consider the coil as the number one source of mold in homes.
At the coil, volumes of organic contaminates collect in two ways: (a) mold and bacteria growth in the damp coil produces sticky enzyme materials for trapping airborne organic material for food (this forms an activated crusty surface on the fins), and (b) the close fitting coil fins collect airborne particles much like a filter.
When the mold colonies grow on the coil, they produce a sticky substance called enzyme mycelium. Enzymes break down proteins and organic compounds. The enzyme mycelium performs two essential functions for molds: (a) the stickiness traps dust particles from the air, and (b) enzymes break the trapped particles into food.
With the dust and enzyme material collecting on the coil, an insulation film covers the fins. This installation prevents an efficient heat exchange between the air and fins and efficiency drops. With such restrictions, the cost of operating a coil can increase by 60%.
Thus, as can be seen, the coil then becomes a major source of airborne contamination (mold spores, enzymes, toxins and bacteria) due to the growth of mold, bacteria at the coil.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant""s acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
Nagy, et al., xe2x80x9cDisinfecting Air with Sterilizing Lampsxe2x80x9d, Heating, Piping and Air Conditioning, Vol. 26., Nos. 1-12, April 1954, pp. 82-87.
Steril-Air, Inc., xe2x80x9cSteril-Air UVC Emitters Product Brochurexe2x80x9d, date unknown, entire brochure.
Sterile-Air, Inc., xe2x80x9cGuide to UVC Emittersxe2x80x9d, date unknown, entire brochure.
Philips Lighting, xe2x80x9cDisinfection by UV-radiationxe2x80x9d, August, 1992, entire paper.
Westinghouse, xe2x80x9cSterilamp(copyright) Germicidal Ultraviolet Tubes Product Brochurexe2x80x9d, March, 1982, entire brochure.
Vig, xe2x80x9cUV/Ozone Cleaning of Surfaces, Treatise on Clean Surface Technology, Vol. 1, 1987, pp. 1-26.
Jensen, xe2x80x9cHVAC Technology is Weapon in Fight Against Tuberculosisxe2x80x9d, ASHRAE Journal, August, 1997, p. 12.
Georgia Tech Research Corporation, xe2x80x9cEmissions from Mold and Fungus May Cause Indoor Air Problemsxe2x80x9d, 1996, entire article.
Ward, xe2x80x9cIs Your Child Allergic to Schoolxe2x80x94Literally?xe2x80x9d, www.townonline.com, January, 1997, entire article.
Layton, xe2x80x9cAllergy and Attention Deficit Hyperactivity Disorder (ADHD)xe2x80x9d, www.allergyconnection.com, 1996, entire article.
Krajick, xe2x80x9cThe Floating Zooxe2x80x9d, Discover, February, 1997, pp. 66-73. Sacramento Municipal Utililty District, xe2x80x9cWater Water Everywhere, But . . . xe2x80x9d,On Center, Second Quarter, 1997, p. 1.
Bayer, et al., xe2x80x9cStudy Suggests Some VOCs Caused by Molds and Fungixe2x80x9d,ASHRAE Journal, October, 1996, p. 12.
An air cleaning apparatus is disclosed including UV lamps, aluminum filters, and a polished aluminum housing. The UV lamps include a U-bend crystal of quartz, ruby, or sapphire contained within a quartz sleeve. Useful substances for containment within the U-bend bulb are mercury, argon, gallium, iron, xenon or krypton. Between the sleeve and lamp, certain gases (nitrogen or atmospheric gases) are contained therein or the area is possibly evacuated. There are advantages and disadvantages to each. By using a mixture of above gases and/or by varying the electrical charge, one can increase the bandwidth to about 240 nm to about 280 nm, including the 265 nm optimum wave length. Further, increased electrical charge can increase bandwidth and spectral line output from 240 nm to 360 nm for more germicidal effect (UVC/UVB).
Polished aluminum filters and chamber walls are also included in this invention. The treated, polished aluminum alloy provides enhanced reflectivity for the UV rays to enhance the irradiation of particulate flowing through the filters and by the lamps. The aluminum filters have an additional special feature in that one side of the filter is of a coarse mesh whereas the other side of the filter is of a fine mesh. Air flow is from the coarse side to the fine side of one filter, past the UV bulbs, through the fine side, and out the coarse side of another aluminum filter and then back into the duct work of an HVAC system. By providing treated, polished aluminum surfaces surrounding the UV lamps, irradiation is enhanced significantly.
An alternate embodiment in the form of a portable air cleaning device is also described herein. The purpose of the portable device is to clean a single room with a similar system as described hereinabove, but also including a fan built into the portable unit to move through the system.
Another embodiment is described wherein a UV lamp array is mounted exterior to a compressor coil of an HVAC system thereby allowing for cleansing of contaminants contained on the coil and fin structure of the compressor. It has been known that this is a breeding ground for microorganisms and cleansing of this breeding ground will enhance cleansing of the entire HVAC system.
By inserting an UVC lamp into the coil region and adding a chemical catalyst, a process of organic xe2x80x9cdustingxe2x80x9d and microbial cleaning takes place at the coil. The process is further enhanced because the aluminum fins are excellent reflectors of the ultraviolet within the coil chamber resulting in UV amplification, with little or no deterioration on the metal itself.
As the air passes the WVC lamp, electrons of a dust, toxins, and microorganism molecules are ejected. Electrons are negative. When the electrons are ejected a positive particle or ion is left behind.
As the circulating air pass through the coil fins, the aluminum oxide fins pick up the charged organic and biological materials coming from the UV light area. The organic material adheres to the aluminum fins for several reasons.
The oxide film in the aluminum has a high propensity to collect electrons that generates an electrostatic polarity. This produces an affinity for either negative or positive ions (depending upon the pH) to the coil fins. Aluminum oxide has the highest advantage over all solid material because it is very stable over a wide range of pH. Normally the pH on the fin surface will be relatively high from the decay of organic materials on the fins, thus attracting positive ions to the coil.
The process on the aluminum oxide mesh is called electronegativity, which forms the basis of electrostatic energy on the filter surface. Electronegativity is based upon the principle of the power of an atom in a molecule to attract elections to itself. The electronegativity of an element depends upon its valence state. Aluminum has an average electronegativity value of 1.61 (near the middle compared to the other element values in the group); oxygen has the second highest value of all elements to attract electrons to itself at 3.44. All coil fins are made of aluminum oxide metal, thus having a very high attraction ability of free electrons to the fins, primarily due to the strength of the oxide (oxygen) to attract elections.
The aluminum oxide fins have an enormous capacity to attract an abundance of free electrons stripped by the UV from the incoming organic and biological particles before getting to the coil. As the aluminum oxide collects more and more electrons, the coil loads up on electrons, becoming primarily negative.
And as the positively charged organic ion material (coming from the UV light area) nears the negatively charged coil, the organic molecules begin adhering to the fins based upon the principle of positive/negative polarity (the electrostatic principle). In other words, the incoming airborne positively charged organic materials are attracted to the negatively charged coil and adhere to the coil fins.
With the dust adhering to the coil fins, the UVC can then begin the breakdown process. The invention then has two methods of breaking apart the hydrocarbon contaminates.
The damaging effects of x-ray and gamma ray radiation are recognized but not fully understood. X-ray, gamma, ultraviolet, infrared and visible light energy fit in a category called electromagnetic energy. They all have the same characteristic of an oscillating energy wave that travels at the speed of light. The difference in each type of wave energy is the wavelength or the distance across the wave. The shorter the distance across the wave body, the shorter the wavelength and the stronger the energy. It is this wavelength difference that results in short-wave x-ray passing through walls, while longer wave lengths of visible light cannot. Short-wave ultraviolet and x-ray can destroy DNA in living microorganisms and break down organic material while visible light cannot.
The science of ultraviolet radiation usage is essentially the science of photochemistry. Photochemistry is defined as a chemical reaction or change in a material induced by the radiation of light energy.
The photochemical process takes place when electrons of a molecule are ejected or changed by the irradiation of light energy, leaving an incomplete and decaying molecule. With the absence of an electron, organic compounds become unstable and fall apart.
All organic particles and microorganisms have a strong reaction to light energy between 180-320 nm. Such molecules are vulnerable to short-wave UV irradiation. The reason: molecular structures depend upon the continued maintenance of a molecular weight. But this weight is altered when UV irradiation reduces the number of electrons orbiting an organic molecule. This causes decay of the material.
Ultraviolet radiation in the C-band (WVC) has properties that alter the cells of living tissue, particularly microbes due to size. WVC radiation ejects electrons and alters the bonds between amino acids in the microbe""s DNA molecules. This renders bacteria, viruses and molds sterile. The cell structure of microbes will continue to degrade in the presence of short-wave UV and will break down into free state ions and/or separate carbon or hydrogen molecules.
One of the reactions is the formation of hydrogen peroxide (H2O2) from the photochemical change of the dust, toxins and microorganism collecting at the coil. When the UV changes molecular electrons of the organic material often hydrogen is ejected from the molecules of the material. These hydrogen radicals then react with ordinary atmospheric oxygen (O2), forming hydrogen peroxide H2O2. The hydrogen peroxide process activates a chain reaction, oxidizing organic material and helping to clean coil surfaces.
Further, the hydrogen peroxide is also converted to hydroxide (OHxe2x80x94), which is a very powerful oxidizing agent.
At the factory or before the coil is installed, the evaporative coil fins are sprayed with a liquid mixture of water and sodium persulfate (Na2S2O8), or potassium persulfate (K2S2O8) or sodium hydroxide (NaOH). These liquid mixtures dry at room temperature on the surface of the coil fins, leaving a residue of the persulfates or sodium hydroxide.
The persulfates, when exposed to UV at wavelengths 100 nm to 320 nm, forms hydrogen peroxide (H2O2). Hydrogen peroxide, however, quickly breaks down into hydroxide (OH) and water (H2O) when exposed to these UV wavelengths.
Under the alternative, the sodium hydroxide, when exposed to short wave ultraviolet, breaks down into sodium (Na) and hydroxide (OH).
The dried crystals of persulfates within the coil fins, when exposed to UV form by products including hydrogen sulfate and hydrogen peroxide (S2O8xe2x88x922+2H2O+UV=2HSO4xe2x88x92+H2O2). The hydrogen peroxide (H2O2) both hydroxide (OH) and water in the presence of UV (H2O2+UV=H2O+OH).
The hydroxide formation is from the UV and persulfates (persulfates to hydrogen peroxides converting to hydroxide in the presence of short wave to medium wave UV) or the sodium hydroxide that have been sprayed on the coil fins. In either case hydroxide is formed in the presence of UV.
Hydroxide is a stable but a very potent one-electron oxidant. The reason hydroxyl ions are so destructive to organic molecules (house dust, toxins and microorganism) is the hydroxide ions xe2x80x9ccapturexe2x80x9d hydrogen molecules from the organic materials, leaving decayed carbon ions. The removal of hydrogen from organic molecules by hydroxide forms even stronger reactive OH bonds as the result of the water at the coil. The process turns into a chain reaction, resulting in continual decay of the organic material by hydroxide formation and converting back to water.
Hydroxide primarily targets organic materials for oxidation. This oxidizing agent thrives by absorbing hydrogen from organic compounds. Hydroxide is perhaps the ideal oxidizer for cleaning organic growth in the evaporation coil without the corrosive effects of ozone. A damp coil is the best environment to experience the full effects of UV. It is in this promising condition that UV energy breaks down the collected organic material, setting off a chain reaction of hydroxide and hydroperoxide formation, which further destroys organic materials.
This means the invention effectively cleans the evaporation coil of organic particle collection and destroys any growth of germs and mold accumulating at the coil. Once clean, the coil remains clean in the presence of the invention.
Accordingly, it is a primary object of the present invention to provide an ultraviolet ray actinism chamber for destroying contaminants thereby.
Another object of the present invention is to avoid the production of ozone in such a system.
Another object of the present invention is to provide increased UV bandwidth to so increase the xe2x80x9ckillingxe2x80x9d power of the UV system.
Another object of the present invention is to maintain a substantially constant temperature around the UV bulb.
Another object of the present invention is to increase UV reflectivity in and around the UV bulbs to enhance the UV irradiation.
Another object of the present invention is to provide self cleaning filters for a UV system.
Another object of the present invention is to provide better, yet shorter lamp lengths to fit in conventional HVAC systems.
Yet another object of the present invention is to enhance the bulb life of a UV bulb for such a system.
Viewed from a first vantage point, it is an object of the present invention to provide an apparatus for purging impurities from ambient air conditions, comprising: a source of radiation in operative communication with the ambient air conditions; and a coating upon which radiation emitted from said source impinges thereon facilitating a chemical reaction.
Viewed from a second vantage point, it is an object of the present invention to provide an a method for purging impurities from ambient air conditions, comprising the steps of: creating turbulent air around an ultraviolet light source; passing the turbulent air adjacent to the ultraviolet light source to create a photochemical reaction.
Viewed from a third vantage point, it is an object of the present invention to provide a self-cleansing filter or evaporative coil prepared by a process comprising the steps of: coating a substrate with a mixture of water and sodium hydroxide or a persulfate; drying the mixture coated in the substrate at room temperature leaving a residue of the persulfate or sodium hydroxide
Viewed from a fourth vantage point, it is an object of the present invention to provide a chamber for cleansing ambient air, comprising, in combination: an air inlet; an air outlet; said chamber interposed and communicating between said inlet and outlet; a source of radiation in said chamber, said chamber imperforate to the radiation; said chamber having an interior surface with means for reflecting substantially all the radiation; and a coating means to enhance the effect of the radiation.
Viewed from a fifth vantage point, it is an object of the present invention to provide a method for coating a filter mesh or an evaporative coil for providing either negative or positive ions depending upon the pH or pOH, the steps comprising: forming a filter mesh or evaporation coil out of aluminum; dipping or spraying the filter mesh or evaporation coil with a liquid mixture to form a film; wherein the liquid mixture is selected from the group consisting of water and sodium persulfate, potassium persulfate and sodium hydroxide.
Viewed from a sixth vantage point, it is an object of the present invention to provide an method of photochemically treating ambient air to purge impurities, the steps comprising: filtering the air; exposing the air to a source of radiation; further filtering the air after exposure to radiation to arrest irradiated particles within the air after irradiation; and further exposing the arrested, irradiated particles to further radiation causing a break down of the molecular structure of said irradiated particles that yields a self-cleansing effect to a structure to which the arrested, irradiated particles were arrested by.
Viewed from a seventh vantage point, it is an object of the present invention to provide a method of treating air with a chemical disposed on an aluminum substrate, the steps comprising: passing air through the aluminum substrate in order to arrest particles or organic molecules; exposing the particles or organic molecules to radiation to cause breakdown of the molecular structure in order to remove particles or organic molecules from the aluminum substrate thus providing a self-cleansing effect.